Topeka ? The list of outside parties that will intervene in the proposed $12.2 billion merger between Kansas City Power and Light and Topeka-based Westar Energy just got longer Tuesday.

The Kansas Corporation Commission granted requests to intervene from Occidental Chemicals, one of the largest industrial electric consumers in the state; Midwest Energy, a utility company that buys electricity from Westar, and two local chapters of the International Brotherhood of Electrical Workers.

Those entities will join at least 15 other entities that have either filed or been granted permission to intervene in the case. The intervenors are mainly large industrial customers, smaller utilities in the region and labor organizations who all say they have a particular interest in the question whether or not the merger is approved and, if so, how it’s structured.

The Kansas Citizens Utility Ratepayers Board, a state agency that represents residential and small business customers, also has intervened.

KCPL’s parent company, Great Plains Energy, is proposing to buy Westar for $8.6 billion, plus $3.6 billion to acquire Westar’s outstanding debt. If approved, the combined company would serve 1.5 million customers in Kansas and Missouri.

KCC, which regulates public utilities in Kansas, is still in the early stages of the approval process. But Missouri regulators are also trying to assert jurisdiction in the case.

Last week, staff of the Missouri Public Service Commission filed an investigative report that was highly critical of the proposed merger, alleging, among other things, that it would violate a 2001 agreement that said KCPL would not acquire any other public utility without prior approval of Missouri regulators.

It is expected that either the Missouri regulatory agency’s staff or the Office of Public Counsel, Missouri’s counterpart to CURB, will file a complaint seeking to block the merger.

Great Plains Energy, however, say Missouri has no jurisdiction in the matter because Great Plains is only a parent, or holding company, that is not subject to Missouri utility regulation.

Meanwhile, Kansas regulators last week issued an order restating the standards they will use in deciding whether to approve the deal. Those include the deal’s impact on such things as the financial stability of the combined company, the local economy and job markets of communities served by the company, public health and safety, and the environment.

KCC is expected to issue its order no later than April 24, 2017. Great Plains and Westar hope to finalize the merger by June 30.